That increases the size for all fonts, but only certain fonts are problematic.
–
notJimAug 6 '12 at 6:16

Do you have this problem with generic fonts like sans-serif, sans etc or with all fonts?
–
Anwar ShahAug 6 '12 at 6:32

1

If I set the font to sans-serif or DejaVu Sans using the Chrome inspector, it appears in the correct size. If I set it to Arial or Helvetica, it appears in the wrong size. I think this might be an issue related to Ubuntu's font substitution.
–
notJimAug 6 '12 at 6:40

But it really is as simple as that. In human language, the XML file tells fontconfig to set the pixelsize of Arial to 13 when any program requests Arial with pixelsize 12. How beautiful.

I would guess there might be a way to tweak the subpixel renderer so that Arial doesn't appear too small at 12 pixels. If there's such a way, it's probably to be found on this crazy wiki page about fontconfig from archlinux. If someone wants to read that page and tell me what to do, I'd happily give them best answer.

For now, I just nuked the mscorefonts.

Here is another approach to getting fonts in Linux to look much more like those from Windows. I may update this answer tomorrow if I have time to try those suggestions.